Free immunology MCQ exam model for basic medical students

Explanation:

• Type I → Correct because it involves IgE and mast cell degranulation.

• Type II → Incorrect because it is antibody-mediated cytotoxicity.

• Type III → Incorrect because it is immune complex–mediated.

• Type IV → Incorrect because it is T-cell–mediated delayed hypersensitivity.

• Type V → Incorrect because it is not a standard classification.

Explanation:

• IgG → Correct because it is the most abundant antibody in blood.

• IgA → Incorrect because it is predominant in secretions.

• IgE → Incorrect because it is involved in allergy.

• IgM → Incorrect because it is first produced but not most abundant.

• IgD → Incorrect because it is present in small amounts.

Explanation:

• Immune system → Correct because immunology focuses on body defenses against pathogens.

• Endocrine system → Incorrect because it deals with hormones.

• Nervous system → Incorrect because it deals with nerve impulses.

• Respiratory system → Incorrect because it deals with breathing.

• Digestive system → Incorrect because it deals with digestion.

Explanation:

• Interferon-gamma → Correct because it activates macrophages.

• IL-2 → Incorrect because it promotes T-cell proliferation.

• IL-4 → Incorrect because it promotes IgE production.

• IL-5 → Incorrect because it activates eosinophils.

• IL-10 → Incorrect because it is anti-inflammatory.

Explanation:

• Artificial active immunity → Correct because vaccination stimulates the body to produce its own antibodies.

• Natural active immunity → Incorrect because it occurs after natural infection.

• Natural passive immunity → Incorrect because it occurs via placenta or breast milk.

• Artificial passive immunity → Incorrect because it involves preformed antibodies.

• Innate immunity → Incorrect because it is non-specific.

Explanation:

• B lymphocytes → Correct because they produce antibodies.

• T lymphocytes → Incorrect because they mediate cell-mediated immunity.

• Macrophages → Incorrect because they perform phagocytosis.

• Neutrophils → Incorrect because they are first-line phagocytes.

• Natural killer cells → Incorrect because they kill virus-infected cells.

Explanation:

• Macrophage → Correct because it is a professional antigen-presenting cell.

• Neutrophil → Incorrect because it is not a professional APC.

• Erythrocyte → Incorrect because it lacks MHC molecules.

• Platelet → Incorrect because it is involved in clotting.

• Fibroblast → Incorrect because it is structural.

Explanation:

• Thymus and bone marrow → Correct because lymphocyte maturation occurs here.

• Spleen and lymph nodes → Incorrect because they are secondary lymphoid organs.

• Tonsils and Peyer’s patches → Incorrect because they are secondary lymphoid tissue.

• Appendix and spleen → Incorrect because appendix is secondary lymphoid tissue.

• Liver and spleen → Incorrect because liver is not a primary lymphoid organ.

Explanation:

• IgG → Correct because it provides passive immunity to the fetus.

• IgA → Incorrect because it is present in breast milk.

• IgE → Incorrect because it mediates allergy.

• IgM → Incorrect because it is too large to cross placenta.

• IgD → Incorrect because it has minimal serum role.

Explanation:

• C9 → Correct because it forms the membrane attack complex causing lysis.

• C1 → Incorrect because it initiates classical pathway.

• C3 → Incorrect because it is involved in opsonization.

• C5a → Incorrect because it is a chemotactic factor.

• C3b → Incorrect because it acts as an opsonin.